Polyhydramnios symptoms result from pressure being exerted within the uterus and on nearby organs.

Mild polyhydramnios may cause few — if any — signs or symptoms. Severe polyhydramnios may cause:

• Shortness of breath or the inability to breathe
• Swelling in the lower extremities and abdominal wall
• Uterine discomfort or contractions
• Fetal malposition, such as breech presentation

Your health care provider may also suspect polyhydramnios if your uterus is excessively enlarged and he or she has trouble feeling the baby.

Some of the known causes of polyhydramnios include:

• A birth defect that affects the baby's gastrointestinal tract or central nervous system
• Maternal diabetes
• Twin-twin transfusion — a possible complication of identical twin pregnancies in which one twin receives too much blood and the other too little
• A lack of red blood cells in the baby (fetal anemia)
• Blood incompatibilities between mother and baby
• Infection during pregnancy

Often, however, the cause of polyhydramnios isn't clear.

Polyhydramnios is associated with:

• Premature birth
• Premature rupture of membranes — when your water breaks early
• Placental abruption — when the placenta peels away from the inner wall of the uterus before delivery
• Umbilical cord prolapse — when the umbilical cord drops into the vagina ahead of the baby
• C-section delivery
• Stillbirth
• Heavy bleeding due to lack of uterine muscle tone after delivery

The earlier that polyhydramnios occurs in pregnancy and the greater the amount of excess amniotic fluid, the higher the risk of complications.